Special service speech transfer equipment for telephone exchange systems

ABSTRACT

A SPECIAL SERVICE SUBSCRIBER CIRCUIT ASSOCIATED WITH EACH SUBSCRIBER IS CONNECTED BY A LINK TO A COMMON SPECIAL SERVICE CIRCUIT. A SPEECH CONNECTION IS FORMED VIA THE SPEECH CONNECTION OF THE TELEPHONE SWITCHING EQUIPMENT THROUGH THE SPECIAL SERVICE SUBSCRIBER CIRCUIT BY DIVERTING THE SPEECH CONNECTION INTO THE SPECIAL SERVICE COMMON CIRCUIT FROM THE SPECIAL SERVICE SUBSCRIBER CIRCUIT THROUGH THE LINK BY FLASHING THE HOOK SWITCH OF THE SPECIAL SERVICE SUBSCRIBER. CALL WAITING AND HOLDING SERVICES ARE PROVIDED ON THE SPECIAL SERVICES SPEECH CONNECTIONS WHICH ARE DIFFERENT FROM THE NORMAL SPEECH CONNECTIONS.

Jan. 30, 1973 SPECIAL SERVICE SPEECH TRANSFER EQUIPMENT FOR TELEPHONEEXCHANGE SYSTEMS Filed Dec. 10, 1969 YUTAKA KIMURA ET AL 7 Sheets-Sheetl L SUB A SPEQAL X SUB B sarzvxce TZUNK suBscmBER LS CHZCLHT SUB c swwcuFRAME TRUNK X UNKB h 3 h S 5mm MAR ED. 6 q coumouaz ZWCE K COMMON Icuzcuw NUMBER 4 GROUP SUB X 33cm g TRUNKX SUB B VKCE @Fflfi -X sus 1 mswncu FRAME WUNK 1i 5 UNK s scm q CONTROLLER SERVCE MARKEQ 6 J COMMON lcuzcuw NUMBEQ 4 g snow #7 mwe/vro/zs, Yum/(4 K/Mum Vow/0 flm/zuM/ Yum/(4M45004 75/20/440 K4M464M/ 45u54/ 0/074 ATTORNEYS 3,714,378 EPHONE Jan.30, 1973 YUTAKA KIMURA E L SPECIAL SERVICE SPEECH TRANSFER EQUIPMENT FORTEL EXCHANGE SYSTEMS 7 Sheets-Sheet 2 Filed Dec. 10, 1969 q 30 .rzou mvi: 5 n: m v2:

wh W WM 1J1 H Q U=m Ti M vii 4 mDw Jan. 30, 1973 YUTAKA KIMURA ETAL3,714,378

SPECIAL SERVICE SPEECH TRANSFER EQUIPMENT FOR TELEPHONE EXCHANGE SYSTEMS7 Sheets-Sheet 3 Filed Dec. 10. 1969 .El 8 (1 SPECIAL SERVICE commouClQCUfl "L AOH A02 COI sourzcg UNK comrzouarz 4 Yum/(,4 K M 705/004/(7/ZUM/ Yum/(4 M45004 ATTORNEYS Jan. 30, 1973 YUTAKA KIMURA ETAL3,714,378

SPECIAL SERVICE SPEECH TRANSFER EQUIPMENT FOR TELEPHONE EXCHANGE SYSTEMSFiled Dec. 10, 1969 7 Sheets-Sheet 4 fig: 36

R0 AlZ All-L b El (E) RETOHI) 02 a LJEhd E T RETOG) -1. I :aE BIZ BH---Lha 022 0 Zl---L8 IZOD RBT T60 TON he: BT

SIG NAL SOURCE Mll/EA/TOXS,

BY Zl/MSoa, M fwd/Sou,

' ATTORNEYS Jan. 30, 1973 YUTAKA KIMURA ETAL 3,714,378

SPECIAL SERVICE SPEECH TRANSFER EQUIPMENT FOR TELEPHONE EXCHANGE SYSTEMSFiled Dec. 10, 1969 7 Sheets-Sheet 5 UNE APPEAR" ANCE BY M5051 0 477[Va/5W, Mfwal [um ATTORNEYS SUB A Jan. 30, 1973 YUTAKA KIMURA ETAL3,714,378

SPECIAL SERVICE SPEECH TRANSFER EQUIPMENT FOR TELEPHONE EXCHANGE SYSTEMS7 Sheets-Sheet 6 Filed Dec. 10, 1969 I. SPEClAL SERVICE J. 6d COMMONcuzcuw 2 I: (E) R] (EH0.

cor

U NK CONTROLLER 4 5 4h O 4 n wmM wmmz Mom; JWHM/ 5w mws wmmw Jan. 30,1973 YUTAKA KIMURA Er SPECIAL SERVICE SPEECH TRANSFER EQUIPMENT FORTELEPHONE EXCHANGE SYSTEMS Filed Dec. 10, 1969 fig: 6b

'7 Sheets-Sheet '7 [R0 AIZ A" w v m RUTH!) '5 I02 |f n E LINK 3 '0 art aQ 512 an Lcc if h 7 7 C 0 Kb a a hat A22 F R Z emz'L ohm E2 165 (E) 825UNE RETIGI) 1 A p FS mfgsmegma i.l l b B22 cc 1 we .IH BY] L pm by] um 3l A REmm oan) uni gil hd i L8 M 1 r IGv y m2 M8 022 \INE b7} APPEARANCEIZOD RBT T60 TONE TGI BT FOQ $HZVICE I l I l I LS smum. somzce 1 mm/N|/E/V70/Z5, Yum/(4 A wu/m ATTORNEYS United States Patent 3,714,378SPECIAL SERVICE SPEECH TRANSFER EQUIP- MENT FOR TELEPHONE EXCHANGESYSTEMS Yutaka Kimura and Yoshio Ariizumi, Tokyo, Yutaka Masuda,Hasuda-machi, Teruhiro Yamagami, Yokohama, and Yasushi Okita, Tokyo,Japan, assignors to Nippon Telegraph and Telephone Public Corporationand Oki Electric Industry Co., Ltd., both of Tokyo, Japan Filed Dec. 10,1969, Ser. No. 883,871 Int. Cl. H04m 3/42 US. Cl. 179-18 B 3 ClaimsABSTRACT OF THE DISCLOSURE A special service subscriber circuitassociated with each subscriber is connected by a link to a commonspecial service circuit. A speech connection is formed via the speechconnection of the telephone switching equipment through the specialservice subscriber circuit by diverting the speech connection into thespecial service common circuit from the special service subscribercircuit through the link by flashing the hook switch of the specialservice subscriber. Call waiting and holding services are provided onthe special service speech connections which are different from thenormal speech connections.

This invention relates to a telephone exchange system, and moreparticularly to a special service control system wherein a specialservice can be connected in an auto matic telephone exchange system.

Though there are various special telephone exchange services, theinvention is described with respect to a callwaiting service and holdingservice.

In the following description relating to a call-waiting service, withtelephone subscribers A, B and C, the subscriber A is a call-waitingservice subscriber and the subscribers B and C may be or may not becall-waiting service subscribers.

Now, while the service subscriber A and the subscriber B are speakingwith each other, there may be an incoming call for the servicesubscriber A from another subscriber C, and an indication thereof (forexample, by a sound or lamp) informing the service subscriber A that anincoming call is made. When the service subscriber A confirms theindication of the incomin call, he sends out a transfer signal (forexample, by placing the telephone on hook). By the above mentionedtransfer signal, the speech connection is transferred and the servicesubscriber A is connected with subscriber C. In this case, a waitingsignal is sent out for the subscriber B to wait. Thereafter, by sendingout a transfer signal, the service subscriber A can freely alternatelytransfer his connection to the subscribers B and C any number of times.The above is the summary of a special service generally called a callwaiting service.

In the following description relating to a holding service, withtelephone subscribers A, B and C, the subscriber A is a holding servicesubscriber and the subscribers B and C may be or may not be holdingservice subscribers.

Now, while the service subscriber A and the subscriber B are speakingwith each other, in case there occurs a need for the service subscriberA to speak with the subscriber C, a dial tone is sent to the servicesubscriber A. Having heard the dial tone, the service subscriber A dialsthe telephone number of the subscriber C to call and speak to thesubscriber C. Thereafter, by sending out a transfer signal, the servicesubscriber A can freely alternately transfer to either of thesubscribers B and C to speak to either one of them any number of times.The

"ice

above is the summary of the function of a special service generallycalled a holding service.

An object of the present invention is to provide an improved telephonespeech path transfer system which provides a special service of the typereferred to.

In a conventional system for realizing a special service, speechtransfer equipment having a special service function has been requiredfor each service subscriber. When it is taken into consideration thatthe special service call usage is less than the general speech callusage, the efficiency of such speech transfer equipment is very low anduneconomical.

A feature of the present invention is that a special service subscribercircuit corresponding to a subscriber and a special service commoncircuit to be used in common by a plurality of subscribers are providedbetween a subscriber telephone and a telephone switchboard and arelinked with each other so that the efiiciency of the special servicecommon circuit may be increased, the equipment cost per servicesubscriber may be reduced and a special service may be providedeconomically.

Another feature of the present invention is that, by a transfer signalfrom a service subscriber, a speech connection is formed in the abovementioned special service common circuit and the above mentionedsubscriber cirouit, and is transferred and connected in the abovementioned special service common circuit so that a special servicecircuit is provided.

The present invention has application to a telephone exchange system andis best adapted particularly to a common controlled atutomatic telephoneexchange system.

The above mentioned and other objects and features of the presentinvention will be made clear by the embodiments of a commonly controlledautomatic telephone exchange system to be explained in detail in thefollowing.

In the accompanying drawings:

FIG. 1 is a block diagram of the first embodiment of the presentinvention showing devices required to make a special service and theiroperating relationships;

FIG. 2 is a diagram showing an embodiment of the special servicesubscriber circuit in FIG. 1;

FIGS. 31: and 3b are a schematic of the special service common circuitembodiment of FIG. 1;

FIG. 4 is a block diagram of the second embodiment of the presentinvention showing devices required to make a special service and theiroperating relationships; 1

FIG. 5 is a diagram showing an embodiment of the special servicesubscriber circuit in- FIG. 4;

FIGS. 6a and 6b are a schematic of the special service common circuitembodiment of FIG. 4.

FIG. 1 shows the first embodiment of and as applied to a commoncontrolled automatic telephone exchange system, and relates to a specialservice subscriber circuit 1 and a special service common circuit 2.Therefore, other devices than those that are required to understand thepresent invention are not shown.

Further, in the following description, the subscriber telephones SUB A,SUB B and SUB C, link 3, link controller 4, switch frame 5, marker 6,number group 7 and trunks 8 and 9 have the same functions as thosealready known in the field of this invention and are not explained indetail.

In this embodiment and the later described second embodiment, the commoncontrolled automatic telephone switchboard is represented by the switchframe 5, marker 6 and number group 7 as is well known to the art.

The special service subscriber circuit 1 has a function of cutting aspeech connection into the special service common circuit 2 by atransfer signal (for example, placing the telephone on hook) from theservice subscriber SUB A or an incoming signal into the service lineappearance LS from the switchboard side to provide a special serviceconnection. Special service subscriber circuit 1 is provided to aspecial service subscriber and is connected to the telephone of specialservice subscriber telephone SUB A. Further, the special servicesubscriber circuit 1.-is connected to the switch frame of theswitchboard through the line appearance L and service line appearance LSon the side opposite the above mentioned side. Further, the specialservice subscriber circuit 1 is connected 'with the special servicecommon circuit 2 through link 3: The line appearance L and service lineappearance LS well-known functions, namely, in the case of an ordinaryspeech, the line appearance L may be used and, in the case of a specialservice, the service line appearance LS may be used. t

A proper number of special service common circuits 2 are set in responseto the service calls of a group of service subscribers so as to be usedin common thereby and have a function of transferring speech connections'by a transfer signal from the service subscriber SUB A.

As mentioned above, the special service subscriber circuit 1 is providedto correspond to the service subscriber. On the other hand, the specialservice common circuit 2 is set so as to be used in common by a group ofa plurality service subscribers. Therefore, they are connected with eachother through the link 3 controlled by the link controller 4.

The following is a description of a call-waiting service.

Now, while the service subscriber SUB A is speaking with the subscriberSUB B (through the service subscriber SUB Aspecial service subscribercircuit 1line appearance L-switch frame 5-trunk 8-subscriber SUB B) ifthere is an incoming call to the service subscriber SUB A through thetrunk 9 and switch frame 5 from the subscriber SUB C, the marker 6receives the telephone number of the service subscriber SUB A by a knownmethod and transfers the telephone number to the number group 7. In thenumber group 7, as a representative circuit is formed by the lineappearance L and service line appearance LS of the switch frame 5corresponding to the service subscriber SUB A, if the service subscriberSUB A is vacant, the number group 7 sends the position informa tion ofthe line appearance L back to the marker 6 and, if the servicesubscriber SUB A is speaking, the number group 7 sends the positioninformation of the service line appearance LS back to the marker 6. Inthis case, as the service subscriber SUB A is speaking with thesubscriber SUB B, the number group 7 sends the position information ofthe service line appearance LS back to the marker 6. The marker 6controls the switch frame 5 from the line position information of theservice line appearance LS in the switch frame 5 and the line positioninformation of the trunk 9 is received by a known method. The trunk 9and the special service subscriber circuit 1 are connected with eachother through the switch frame 5. By the above mentioned connection, thespecial service subscriber cir- Hit 1 receives the incoming signal tothe service line appearance LS from the subscriber SUB C and initiatesoperation of the link controller 4. The link controller 4 selects andobtains access to the vacant special service common circuit 2 andconnects the special servige subscriber circuit 1 and the specialservice common circuit 2 with each other by closing the link 3.

Thus, the speech connection is cut into the special service commoncircuit 2 by the special service subscriber circuit 1 and the servicesubscriber SUB A is connected with the subscriber SUB B through thespecial service common circuit 2. A network comprising the servicesubscriber SUB A-specia-l service subscriber circuit l-link 3-specialservice common circuit 2--link L's-special service subscriber circuit1--line appearance Lswitch frame 5trunk 8-subscriber SUB B-is formed.When the above mentioned speech route is made, the special servicecommon circuit 2 sends an incoming call-indicating signal to the servicesubscriber SUB A who is speaking and in- 4 forms him that there is anincoming call from the subscriber SUB C.

An example of the incoming call-indicating signal is as follows. Thespecial service common circuit 2 first sends out a calling signal forabout one second to the service subscriber SUB A and then sends out anintermittent originating call signal to the service subscriber SUB A andsub scriber SUB B until the service subscriber SUB A responds to thecalling subscriber SUB C. r

If the service subscriber SUB A sends out a transfer signal bydepressing the hook, the special service common circuit 2 receives thetransfer signal, holds the line appearance L side which is speaking andtransfers and connects the speech path connection on the servicesubscriber SUB A side to the service line appearance LS side. Theservice subscriber SUB A responds to the subscriber SUB C through thespeech network the service subscriber SUB A-special service subscribercircuit 1link 3special service common circuit 2-link 3special servicesubscriber circuit 1service line appearance LSswitch frame 5-trunk9subscriber SUB C.

Thereafter by sending out a transfer signal by depressing the hook, theservice subscriber SUB A can freely alternately transfer to thesubscribers SUB B and SUB C through the special service common circuit 2to speak with them any number of times.

Further, when the service subscriber SUB A disconnects the speech pathto the subscriber SUB C, the subscriber SUB A flashes the telephonehook-switch for a longer duration than the duration of the transfersignal after the speech path between the subscriber SUB A and thesubscriber SUB C was formed. By the above men tioned operation thespecial service common circuit is restored. Then the speech path betweenthe subscriber SUB A and the subscriber SUB B is formed.

The following is a description of a holding service. When the servicesubscriber SUB A speaking with the subscriber SUB B through the speechroute-service subscriber SUB Aspecial service subscriber circuit 1-lineappearance L-switch frame S-trunk 8subscriber SUB B-is to call thesubscriber SUB C, the service subscriber SUB A tells the othersubscriber SUB B who is being spoken to that the speech shall beinterrupted in order to call the third person and then sends out atransfer signal to the special service subscriber circuit 1 by bookingthe telephone. The special service subscriber circuit 1 receives thetransfer signal and initiates operation of the link controller 4. Thelink controller 4 selects and obtains access to the vacant specialservice common circuit 2 and connects the special service subscribercircuit 1 and special service common circuit 2 with each other byclosing the link 3.

Thus the speech connection is formed within the special service commoncircuit 2 by the special service subscriber circuit 1 and a networkthrough the service subscriber SUB A-special service subscriber circuit1link 3special service common circuit 2-link i i-special servicesubscriber circuit 1-line appearance L-switch frame 5-trunk 8-subscriberSUB B is formed. As soon as the above mentioned network is made, thespeech connection is transferred to the service line appearance LS sideby the special service common circuit, the line appearance L side isheld and a waiting signal is sent to the subscriber SUB B. The servicesubscriber SUB A is connected to a Well known originating call register(not illustrated) through the transferred service line appearance LS andreceives an originating-call signal the same as in well knownoriginating call connections. Thereafter, by dialing the telephonenumber of the third subscriber SUB C, the service subscriber SUB A isconnected with the sub scriber SUB C by well known exchange connectingmethods. That is to say, a network through the service subscriber SUBA-special service subscriber circuit 1-link 3-special service commoncircuit 2-link 3-special service subscriber circuit 1service iineappearance LS- switch frame 5trunk 9subscriber SUB C is formed and theservice subscriber SUB A can speak with the subscriber SUB C.

Thereafter, the operation is the same as described above in thecall-waiting service. That is, by sending out a transfer signal byhooking the telephone receiver, the service subscriber SUB A can freelyalternately transfer to the subscriber SUB B and SUB C through thespecial service common circuit 2 and can speak with either of them anynumber of times.

Further, when the service subscriber SUB A disconnects the speech pathwith the subscriber SUB C, the subscriber SUB A flashes the telephonehook-switch for a longer duration than the duration of the transfersignal after the speech path between the subscriber SUB A and thesubscriber SUB C was formed. By the above mentioned operation thespecial service common circuit is restored. Then, the speech pathbetween the subscriber SUB A and the subscriber SUB B is formed.

The first embodiment of the invention is described in detail hereinafterwith reference to the specific circuit diagrams shown in FIGS. 2 and 3.

In the indicating method which is also the same in FIGS. 5 and 6, therelay is represented by a capital letter, its contact is represented bythe lower case alphabet letter and the ditferent windings of the samecomponent part are represented by such letters as I, II and III.

CALL-WAITING SERVICE In FIG. 2, when the service subscriber SUB A is offhook, it is connected to the switchboard side through the lineappearance L through the terminal A10retardation coil RET (I)-contactsp--terminal Atelephone SUB A-terminal B00-contacts s l -rectifierD2-relay A(I)rectifier D2-terminal B10to form a well-known subscriberoriginating call and initiates operation of an originating call registernot illustrated.

In the special service subscriber circuit 1, as soon as the servicesubscriber SUB A is off hook, the relay A is operated by the relay AIinserted in the speech line. The contact a of the relay A is made andthe relay B operates through groundcontact a contact b --rectifier D5-relay AAbattery. The contact an of the relay AA is made and the relay Boperates through ground-contact (I -contact aa rectifier D3relayBbattery.

When the service subscriber SUB A is connected to the originating callregister, ground is connected from the switchboard side through acontrol line, that is, the line appearance L applied to the terminal Cto operate relay BY through ground-terminal C10-contact sp rectifierD7-relay BY-battery.

By dialing the telephone number of the other subscriber SUB B, as wellknown, the service subscriber SUB A is connected with the subscriber SUBB in an ordinary speech connection. In this case, until the servicesubscriber SUB A calls the subscriber SUB B and isconnected thereto,ground appears at the service line appearance through the ground-contactby contact e --terminal C20. The indication of the connection isprovided at the switchboard side so that the incoming of a new call maybe prevented while the service subscriber SUB A is calling thesubscriber SUB B. That is to say, when the subscriber SUB B responds, apulse for the charge is sent out to the terminal C10 of the lineappearance L from the switchboard and therefore the relay E operatesthrough the terminal C10-contact sp -rectifier D6relay E(I) ground andis self-held through the ground-contact by contact c --relayE(II)battery. Therefore, the above described grounding of the terminal Cis cut by the operation of the contact e and the terminal C20 isindicated as vacant.

Now, when there is an incoming call from the subscriber SUB C to theservice subscriber SUB A who is speaking with the subscriber SUB B,ground appears at terminal C20 through the switchboard and, in thespecial service 6 subscriber circuit 1, a ground connection is completedto the link controller 4 through the terminal C20-contact e contact spterminaI ST to signal and start the link controller 4.

The link controller 4 starts the vacant special service common circuit2, detects whether there is the ground connection in the terminal BY ofthe special service common circuit 2 shown in FIG. 3 and is connected tothe special service common circuit 2 if there is the ground connection.The link controller 4 connects ground via the terminal CST of thespecial service common circuit 2 to operate the relay B of that circuit.The contact 12 of the relay B operates, the relay ICC operates throughgroundcontact rl contact -rectifi.er D -relay ICCbattery, its contact isclosed and the loops of the speech lines of circuit 2 are closed. Whenthe contact b is closed, the relay RCV operates through ground-contactby2 contact b contact ch contact hd relay RCVbattery.

The link controller 4 is connected to the above mentioned vacant specialservice common circuit 2, and at the same time closes the links 3 andconnects the special service subscriber circuit 1 and special servicecommon circuit 2 with each other.

Now, by the operation of the relay ICC, terminal C02 is ground throughthe groundcontact icc termina1 C02, and ground appears at relay SP inFIG. 2 through the link 3 (C01), the relay SP operates and the link 3 isalso held by a known means by being grounded.

When the relay SP operates, the speech connection on the servicesubscriber SUB A side is transferred in the special service subscribercircuit 1 by the contacts sp and sp and is connected into the specialservice common circuit through the links 3 (A01 and B0 Briefly, a loopthrough ground-relay A(I) of the special service common circuit 2contactb contact iccterminal B02-link 3 (BOD-contact sp of the special servicesubscriber circuit 1terminal B00telephone SUB A- terminal A00contactsp-link 3 (A01)-terminal A02 of the special service common circuit2-contact b--relay A(II)-battery is made and the relay A in FIG. 3operates. When the relay A operates, the relay HT operates throughground-contact a relay HT-battery.

The speech connection on the switchboard side is connected to theterminal A12--contact eml-retardation coil RETO(II)contact b resistanceR0relay E1:(I)contact by .l--contact aretardation coil RETO(I)contacture -terminal 12 of the special service common circuit 2 in FIG. 3through the links 3 (A11 and B11) from the terminals A10 and B10 of thespecial service subscriber circuit 1 in FIG. 2 to make a direct currentcircuit which becomes a holding loop for the switchboard side. Asmentioned above, the speech c0nnection between the service subscriberSUB A and subscriber SUB B who are speaking through the special servicesubscriber circuit 1 is connected into the special service commoncircuit 2 through the link 3 so that the service subscriber SUB A mayspeak with the subscriber SUB B through the special service commoncircuit 2.

Now, by the operation of the relay ICC in FIG. 3, as the contact icc ismade, the relay BY1, operates through the ground-contact rl contactb11-rectifier D11- contact icc relay BY1battery. When the relay BY1operates, the relay RL operates through the ground-contact ht -rectifierD7-contact by1 relay RL(H)relay RL(I)--battery.

When the link of the special service subscriber circuit 4 and specialservice common circuit 2 is completed, on the line appearance L side therelay BY1 is held through ground (switchboard)line appearanceL--terminal C10 of the special service subscriber circuit 1link 3 (C11)terminal C12 of the special service common circuit 2- contact by l-rectifier D10-contact icc relay BY1 battery. On the service lineappearance LS side, the relay BY2 operates through ground(switchboard)service line appearance LS-terminal C20 of the specialservice subscriber circuit 1--link 3 (C21)--terminal C22 of the specialservice common circuit 2-rectifier BIZ-relay BY2battery.

When the speech connection is connected into the special service commoncircuit 2, the speech between the service subscriber SUB A andsubscriber SUB B is interrupted temporarily, an incoming call signal(calling signal) is sent out to the service subscriber SUB A and thespeech between them is resumed after about 1 second.

However, until the service subscriber SUB A responds to the subscriberSUB C, a service signal is mixed into the speech. That is, in thecircuit in FIG. 3, as soon as the speech path is transferred, the relayBY2 operates, the above mentioned holding circuit of the relay RCV isopened by the contact 12312 and, after a time interval (about 2seconds), the relay RCV recovers slowly. Meanwhile, the speechconnection is interrupted at the contacts by2, by2 vrb and rcv of thespeech connection, the calling signal (through the terminal TGO-relayA(III)--contact hd"-contact rcv --terminal RBT) from the signal sourceflowing to the relay A(III) and the service signal (through the terminalTGO-relay A(IlI)-contact hd contact rev -contact chm terminal 120 DT)from the signal source are led to the relays A(I) and (II), the callnumber is transmitted to the service subscriber SUB A as an incomingcall indicating signal and the service signal is transmitted to theservice subscriber SUB A and subscriber SUB B. In the speech line inFIG. 3, a band-pass filter is inserted so that, in the case oftransmitting the incoming call indicating signal, the speech betweenboth subscribers may not be interrupted.

Here, if the service subscriber SUB A sends the transfer signal to thespecial service common circuit 2 through the special service subscribercircuit 1 and link 3 in order to respond to the incoming call byflashing the telephone receiver, the loop through the ground-relay A(I)of the special service common circuit-contact b -contact icc-termina1B02-link 3 (B01)--contact sp of the special service subscriber circuit1-terminal BOG-telephone SUB A-terminal Acontact splink 3 (A01)terminalA02 of the special service common circuit 2--contact brelay A(II)batteryis momentarily interrupted and the relay A recovers and then operatesagain. The momentary interruption means that interruption between theslow recovery time of the relay HT and the recovery time of the relay Bin the special service common circuit 2. That recovery time is about 100milliseconds to 1 second. The lower limit is provided to allow theapparatus unable to function by dial pulses in the case of using arotary dial telephone. It is possible in the case of a push-button typetelephone to make the lower limit less than 100 milliseconds.

Even if the relay A in the special service common circuit 2 isrecovered, the relay CH operates through groundcontact rl -contact Ju-contact cha relay CH-battery and, if the above mentioned operatingcircuit of the relay A is made again by the flashing of the servicesubscriber SUB A telephone receiver, the relay A operates again and therelay HT operates. By the operation of the relay HT, the relay CHAoperates through groundcontact rl contact ht contact chcontact Cha-relay CHA-battery. The relay CH is held through ground-contact rl-contact ltd-contact chcontact cha -relay CHbattery 11 and the relay CHAis held through ground-contact rP-rectifier Dl-contact ch --contact charelay CHAbattery. When the relay CHA operates, the relay CHM operatesthrough ground-contact cha contact ht -contact by2 relay CHM-battery andis held through groundcontact chm --contact by2 -relay CHMbattery. Bythe operation of the relay CHA, its contacts cha and cha aretransferred, the speech connection between the service subscriber SUB Aand subscriber SUB B is interrupted and the speech connection of theservice subscriber SUB A is transferred to the service line appearanceLS side.

That is to say, the speech connection of the service subscriber SUB A istransferred to the speech connection through the telephone SUBA-terminal A00 of the special service subscriber circuit 1contactsp--link 3 (A01)-terminal A02 of the special service common circuit2-contact b-condenser CU-contact by2contact rcvcontact chacontact mi-terminal em2 contact A22-link 3 (A21)--terminal A20 of the specialservice subscriber circuit 1service line appearance LS-switch frame5trunk 9telephone SUB C- trunk 9switch frame 5--service line appearanceLS terminal B20 of the special service subscriber circuit link 3(B21)terminal B22 of the special service common circuit 2contact icccontact ca -contact cha -contact rcv contact by2 -condenser C1contact bcontact z'cc--terminal B02link 3 (B01)- contact sp of the specialservice subscriber circuit 1- terminal B00-telephone SUB A.

Further, by the operation of the relay CHM, the contacts chm and chm areclosed so that the service subscriber SUB A may respond to thesubscriber SUB C. That is, a direct current circuit through thetelephone SUB Ctrunk 9switch frame 5-service line appearance LS-terminalB20 of the special service subscriber circuit 1link 3 (B21)terminal A22of the special service common circuit 2contact em2 contact 12d contactshril -retardation coil RETl (ID-resistance R8--contact hd retardationcoil RETl (I)--contact chm contact rl -contact c contact icc terminalB22link 3 (B21)terminal B20 of the special service subscriber circuit1-service line appearance LS-switch frame 5-trunk 9telephone SUB C ismade so that the service subscriber SUB A and subscriber SUB C areinterconnected.

Moreover, the speech connection between the service subscriber SUB A andthe subscriber SUB B is disconnected and the subscriber SUB B is held bythe connection through the telephone SUB 'Btrunk 8switch frame 5lineappearance Lterminal A10 of the special service subscriber circuit1-link 3 (A11)terminal A12 of the special service common circuit2contact emlretardation coil RETO (II)-contact b -resistance R0- relayE1 (I)contact by1contact a -retardation coil RETO (I)-contact fee-terminal B12link 3 (B11)- terminal B10 of the special servicesubscriber circuit 1 line appearance L-switch frame 5trunk 8te1ephoneSUB B.

Further, from the signal source, a signal flows through the signalsource-terminal TONE-contact sha -contact byl -retardation coil RETO(II)--terminal TGI- signal source and, to the subscriber SUB B, awaiting signal fed to the retardation coils RETO (I) and (II) istransmitted through the speech connection.

Next, when the service subscriber SUB A issues a transfer signal by theflashing of the telephone receiver in order to return the speechconnection from the subscriber SUB C to the subscriber SUB B, in thespecial service common circuit 2, as mentioned above, the relays A and'HT recover and operate again. When the relay HT recovers, the relay CHAis held through the ground contact rl contact ht contact cka relayCHAbattery, but the relay CH recovers by disconnection of the holdingcircuit. Thereafter, when the relay HT operates, the above mentionedholding circuit of the relay CHA is also disconnected, the servicesubscriber SUB A is connected with Waiting subscriber SUB B. Thesubscriber SUB C which has the speech connection with the servicesubscriber SUB A is disconnected and is held by the direct currentcircuit through the retardation coils RETI (I) and (II) as mentionedabove and a waiting signal from the signal source flowing through thesignal sourceterminal TONE-contact cha retardation coil RETI(ID-terminal TG1signal source is provided to the retardation coils RETI(I) and (II) and is sent to the subscriber SUB C through the speechconnection.

In the same manner, if the service subscriber SUB A flashes thetelephone receiver again, he can hold the subscriber SUB B, can speakwith the subscriber SUB C and can speak any number of times byalternately transferring the connection. When the service subscriber SUBA has completed speaking with the subscriber SUB C and wants todisconnect the subscriber SUB C, if a flashing of the telephone receiverlonger than the transfer signal is made during the speech connectionwith the subscriber SUB C, the special service common circuit 2 and link3 are disconnected and the service subscriber SUB A returns to theoriginal speech connection which is not through the special servicecommon circuit 2 with the subscriber SUB B as explained above, thecircuit, with the service subscriber SUB A on-hook, in the specialservice common circuit 2, the relays A and HT recover. When the relay HTrecovers, the holding circuit of the relay B is disconnected and therelay B slowly recovers in about 1 second. The special service commoncircuit 2 does not recover with the recovery of the relay B but recoverswith the recovery of the relay RL. However, the relay RL has a slowrecovery time of seconds.

Now, with the recovery of the relay B, the relay C operates through thegroundcontact b contact cha contact chu -rectifier D5.contact ch contactb relay Cbattery. However, when the relays A and HT recover as mentionedabove, the relay CH recovers and the relay CHA is held.

Then, when the service subscriber SUB A off-hooks, the relays A, HT andB operate as mentioned above and the relay CHA recovers as mentionedabove. The holding circuit of the subscriber SUB C is ditferent from theabove description depending on the operation of the relay C and changesto the route through the telephone SUB C- trunk 9switch frame 5serviceline appearance LS- terminal A20 of the special service subscribercircuit 1- link 3 (A21)-terminal A22 of the special service commoncircuit 2contact em2 contact hd contact chm -retardation coil RETl (II)resistance R8-contact MI -retardation coil RETI (I)--contact chm contactrl contact c contact b contact icc terminal B22-link 3 (B21)terminal B20of the special service subscriber circuit 1service line appearance LS-switch frame 5trnnk 9telephone SUB C but, by the operation of the relayB, the contact b breaks and the above mentioned direct current loop isdisconnected.

When the direct current loop is eliminated, the ground which wasconnected to the control line of the service line appearance LS, thatis, to the terminal C22 of the special service common circuit 2,vanishes and the relay BY2 recovers. When the relay BY2 recovers by thecontact by2 the holding circuit is disconnected and relay ICC recoversand, as the ground of the terminal CO2 of the special service commoncircuit -2 holding the link 3 is disconnected by the contact icc thelink 3 recovers. Then the relay SP of the special service subscribercircuit 1 recovers, the contacts sp and sp recover, the speechconnection from which the special service common circuit 2 is separatedreturns and the relay A of the special service subscriber circuit 1 inthe speech line operates so that the service subscriber SUB A may speakwith the subscriber SUB B through the speech connection passed throughthe initial special service subscriber circuit 1. The separated specialservice common circuit 2 can be prepared for a special serviceconnection from another subscriber.

HOLDING SERVICE While the service subscriber SUB A is speaking with thesubscriber SUB B through the special service subscriber circuit 1 inFIG. 2 the same as with the callwaiting service, when, depending on thecontents of the speech, the service subscriber SUB A wants to call and10 consult the subscriber SUB C as a third person, the servicesubscriber SUB A flashing the telephone receiver.

When the speech loop is momentarily disconnected by the flashing of thetelephone receiver, the relay A in the special service subscribercircuit II in FIG. 2 recovers and the relay K operates through thegroundcontact [2 contact al -contact 8 COl'.liaCt k -relay K(I)resistance R battery.

Further, for the line appearance L side, the momentary disconnection ofthe speech loop by the flashing of the receiver is made through theterminal A10-contact sp retardation coil RET (II)contact e -contactkrectifier D1condenser CM1-rectifier Dl-terminal B10 until the relay Koperates. After the relay K operates, a direct current loop through theterminal A10contact sp -retardati0n coil RET (II)-contact e -contactkresistance RZ-contact b-terminal B10 is made so as to prevent thedirect current circuit from being momentarily disconnected on theswitchboard side.

When the relay A operates again, the link controller 4 is actuated fromthe special service subscriber circuit 1 through the groundc0ntact by--contact a -contact b -contact k rectifier D8contact sp terminal ST ofthe link controller 4. Further, through the ground-con tact by contact a-contact b contact k rectifier D9terminal HD of the link controller 4,the holding information is sent to the link controller 4.

As described above in the case of the call-waiting service, when thelink controller 4 is actuated from the special service subscribercircuit 1, it connects the vacant special service common circuit 2 andconnects the ground from the terminal CST of the special service commoncircuit 2 in FIG. 3 and operates the relay B. At the same time, the linkcontroller 4 sends out the holding information via the ground to theterminal HD of the special service common circuit 2 and operates therelay HD.

In the special service common circuit 2 in FIG. 3, by the operation ofthe relay HD, the relay ICC operates through the ground-contact hd--relay ICC-battery. Further, the relay CH operates through thegroundcontact chm rectifier DO-contact hd -relay CHbattery.

When the relay ICC operates, as described above in the call-waitingservice, the relay SP operates through the ground-contact icc terminalC02-link 3 (C01)- relay SP (II) of the special service subscribercircuit 1relay SP (I)battery and, by the contacts rm and sp the speechconnection is diverted into the special service common circuit 2 fromthe special service subscriber circuit 1. That is, the speech connectionis diverted into the special service common circuit 2 through the routethe ground-relay A (I)-contact b -contact icc terminal B02 of thespecial service common circuit 2 link 3 (BOD-contact sp of the specialservice subscriber circuit 1terminal B00-telephone SUB A-terminal A00 ofthe special service subscriber circuit 1contact splink 3 (A01)terminalA02 of the special service common circuit 2contact brelay A (II)batteryand the relay A of the special service common circuit 2 0perates.

Moreover, as soon as the relay SP of the special service subscribercircuit 1 operates, an electric current flows to relay K (II) connectedin parallel, the relay K-(I) is reversely excited, the relay K recoversand the starting route from the special service subscriber circuit 1 tothe link controller 4 is disconnected.

On the line appearance L side of the switchboard, as in the case of thecall-Waiting service, a direct current loop is made through the lineappearance Lterminal A10 of the special service subscriber circuit1-link 3 (AID-terminal A12 of the special service common circuit2contact em1retardation coil RETO (II)- contact b resistance R0relay E1(I)contact by'1 contact a -retardation coil RETO (I)contact icc terminalB12-link 3 (BID-terminal B10 of the special 1 1 service subscribercircuit 1--line appearance L subscriber SUB B is held.

In the special service common circuit 2, when the relay ICC operates,the relay BYI operates through the ground-contact r1 --contact b-rectifier D11contact icc -relay BY1-battery and is held by the groundof the switchboard terminal C12 contact by l' rectifier DIG-contact iccrelay BY1battery. When the relay BYl operates, the relay RL operatesthrough the groundcontact hi -rectifier D7-contact by1 1'elay RL (II)-relay RL (I)-battery.

In the case of this holding service, as soon as the speech connection isdiverted into the special service common circuit 2, the speechconnection is transferred from the and the 'line appearance L side tothe service line appearance LS side in the special service commoncircuit 2. That is, when the relay HT operates, the relay CHA operatesthrough the groundcontact rl -contact ht -contact chcontact clad-relayOHAbattery and is held through the ground-contact rl -rectifierDl-contact ch contact cha --relay CHA-battery. When the relay CHAoperates, the relay CHM operates through the groundcontact alia -contactht --contact hd -re1ay CHM--battery. Subscriber SUB A is transferred bythe operation of the relay CHA to make a route through the service lineappearance LSterminal A20 of the special service subscriber circuit1-link 3 (A21)-terminal A22 of the special service common circuit2contact em2 contact hip-contact aa contact aid-contact cha contactby2condenser (IO-contact b-terminal A02- link 3 (A01)contact sp of thespecial service subscriber circuit 1terminal A00telephone SUB A-terminalB00 of the special service subscriber circuit 1- contact sp --lin'k 3(B01)-terminal B02 of the special service common circuit 2contacticccontact b -condenser (ll-contact by2 contact dia -contact aa contacticc terminal B-22--link 3 (B21)terminal B20 of the special servicesubscriber circuit 1-service line appearance LS and is connected to theservice line appearance LS.

In the direct current loop for the switchboard side, when the relay CHMoperates, a connection through the switchboardservice line appearanceLSterminal A20 of the special service subscriber circuit 1link 3(A2l)terminal A22 of the special service common circuit 2contact em2contact hd -contact aa contact aa contact chm retardation coil RETI(Il)resistance RS-relay E2 (I)-contact hd retardation coil RETI(I)contact chm -contact rF-contact c contact icc terminal B22-link 3(B21)terminal B20 of the special service subscriber circuit 1-serviceline appearance LS-switchboard is formed and the service subscriber SUBA connects and actuates an originating call register (not illustrated)of the switchboard by a well known exchange connecting method. Afterhearing the originating call signal sent from the originating callregister, by dialing the telephone number of the subscriber SUB C, theservice subscriber SUB A can call the subscriber SUB C by a wellknownexchange connecting method.

Thereafter, the same as with the call-waiting service, while the servicesubscriber SUB A is speaking with the subscriber SUB C, a waiting signalis sent to the subscriber SUB B.

Thereafter, when the service subscriber SUB A wants to have thesubscriber SUB C wait and to speak with the original subscriber SUB B,the same as with the callwaiting service, if the telephone receiver isflashed, the subscriber SUB C can be held and the speech connection withthe subscriber SUB B can be returned. It is needless to say that, inthis case, a waiting signal is sent to the subscriber SUB C.

Further, as in the case of the call-waiting service, the operation isthe same in that the above mentioned speech transfer can be made anynumber of times alternately between the subscriber SUB B and subscriberSUB C.

FIG. 4 shows the second embodiment of the present invention as appliedto a common controlled automatic telephone exchange system. In thissecond embodiment, the service line appearance LS in the firstembodiment shown in FIGS. 1 to 3 can be used in common by a plurality ofsubscribers so that it may be more economical than the first embodiment.

Therefore, it is understood that this second embodiment is differentfrom the first embodiment in the components relating to the service lineappearance LS but has substantially the same formation and functionswith-respect to the other parts as is apparent from the followingdescription.

The special service subscriber circuit 1 functions so that, in the caseof forming a special service, the speech connection is diverted into thespecial service common circuit 2 by the transfer signal from the servicesubscriber SUB A, or the incoming signal to the service line appearanceLS from the switchboard side.

The special service subscriber circuit 1 corresponds to the servicesubscriber and is connected with the service subscriber telephone SUB A.The special service subscriber circuit 1 is connected to the switchframe 5 of the switchboard through the line appearance L on the sideopposite the above mentioned side and is further connected with thelater described special service common circuit 2 through the link 3.

A proper number of the special service common circuits 2 are set inresponse to the service call number of a group a number of servicesubscribers so as to be used in common by them and transfer the speechconnection with the transfer signal from the service subscriber SUB A.Further, the special service common circuit 2 is connected to the switchframe 5 of the switchboard through the service line appearance LS.

As mentioned above, the special service subscriber circuit 1 correspondsto the service subscriber and, further, the special service commoncircuit 2 is set so as to be used in common by a group of a number ofsubscribers. Therefore, there is no 1:1 correspondence between them.Therefore, they are connected with each other through the link 3controlled by the link controller 4.

The line appearance L corresponds to the service subscriber and theservice line appearance LS corresponds to a group of a number of servicesubscribers, that is, to the special service common circuit 2. They havesuch a two-circuit representing function as is well-known so that, inthe case of ordinary speech, the line appearance L may be used and, inthe case of a special service, the service line appearance may be used.

The other devices not described in FIG. 4 have already been described inthe first embodiment.

The following is a description of the call-waiting service.

Now, while the service subscriber SUB A is speaking with the subscriberSUB B through the service subscriber SUB A-special service subscribercircuit 1line appearance Lswitch frame 5trunk 8-subscriber SUB B, ifthere is an incoming call to the service subscriber SUB A through thetrunk 9 and switch frame 5 from the subscriber SUB C, by a known method,the marker 6 receives the telephone number of the service subscriber SUBA and transfers it to the number group 7. In the number group 7, arepresentative circuit is formed of the line appearance L of the switchframe 5 corresponding to the subscriber SUB A and the service lineappearance LS of the switch frame 5 corresponding to the special linecommon circuit 2 and, therefore, as in the first embodiment, the numbergroup 7 sends the position information of the service line appearance LSback to the marker 6. At the same time, in the number group 7, as it canbe recognized from the telephone number of the service subscriber SUB Athat the service subscriber SUB A is a callwaiting service subscriberthe information that the service subscriber SUB A is a call-Waitingservice subscriber is sent to the marker 6 from the number group 7. Inthe marker 6, the switch frame is controlled from the positioninformation of the service line appearance LS in the switch frame 5 andthe position information of the trunk 9 separately received by a knownmethod. The trunk 9 and special service common circuit 2 are connectedwith each other through the switch frame 5.

Next, as the marker 6 has received the call-waiting service informationfrom the number group 7, it does not recover but it connects with thenumber group 7 again and transfers the telephone number of the servicesubscriber SUB A to the number group 7. At this time, as the numbergroup 7 is controlled from the marker 6 so as to make no representativeselection, the position information of the line appearance L of theservice subscriber SUB A is transferred to the marker 6 from the numbergroup 7. The marker 6 connects ground to a control line other than theknown control line of the service subscriber SUB A through the lineappearance L from the above mentioned information. As that control lineis connected to the special service subscriber circuit 1, the specialservice subscriber circuit 1 is connescted to ground and actuates thelink controller 4. The link controller 4 connects the special servicesubscriber circuit 1 corresponding to the service subscriber SUB A withthe special service common circuit 2 by closing the link 3. Thus thespeech connection is diverted into the special service common circuit 2by the special service subscriber circuit 1 and, as in the firstembodiment, the service subscriber SUB A can speak with the subscriberSUB B through the special service common circuit 2. Thereafter, thesending of the incoming call indicating signal, the flashing operationof the service subscriber SUB A telephone receiver and the holding ofthe subscriber SUB B are the same as in the case of the firstembodiment.

However, it is apparent that the speech connection, after beingtransferred and connected in the special service common circuit 2, isthrough the service subscriber SUB Aspecia1 service subscriber circuit1link 3- special service common circuit 2service line appearanceLS--switch frame 5trunk 9subscriber SUB C.

Thereafter, such operations as the transferring of the speechalternately to the subscribers SUB B and SUB C and of diverting thesubscriber SUB C are the same as in the first embodiment and shall notbe explained further.

The following is a description of a holding service.

When the service subscriber SUB A speaking with the subscriber SUB Bthrough the speech route through the service subscriber SUB A-specialservice subscriber circuit 1line appearance Lswitch frame 5-trunk 8subscriber SUB B wants to call the subscriber SUB C, the servicesubscriber SU-B A tells the subscriber SUB B that the speech connectionwill be interrupted in order to call the third person and then theservice subscriber SUB A sends a transfer signal by flashing thereceiver and thereby signaling the special service subscriber circuit 1.The special circuit subscriber circuit 1 receives the transfer signal,holds, and actuates the link controller 4. The link controller 4 selectsa vacant special service common circuit 2 and connects the specialservice subscriber circuit 1 with the special service common circuit 2by closing the link 3. Thus the speech path is diverted into the specialservice common circuit 2 by the special service subscriber circuit 1 anda connection through the service subscriber SUB A-special servicesubscriber circuit 1link 3-special service common circuit 2--link3-special service subscriber circuit 1line appearance Lswitch frame 5trunk 8-subscriber SUB B is formed. As soon as the above mentionedconnection is made, the speech connection is transferred to the serviceline appearance LS side in the special service common circuit 2, theline appearance L side is held and a waiting signal is sent to thesubscriber SUB B.

Moreover, at the same time, the service subscriber SUB A is connected toa well-known originating call register (not illustrated) through theservice line appearance LS connected directly with the special servicecommon circuit 2.

The subsequent operations are the same as in the first embodiment.

However, it is apparent that the connection between the servicesubscriber SUB A and subscriber SUB C is through the service subscriberSUB A-special service subscriber circuit 1link 3special service commoncircuit 2-- service line appearance LS-switch frame 5trunk 9- subscriberSUB C.

The second embodiment shall be explained with reference to the circuitdiagrams shown in FIGS. 5 and 6.

FIG. 5 shows the special service subscriber circuit 1 and is exactly thesame as FIG. 2 of the first embodiment except that the connection to theservice line appearance LS is eliminated. However, a control line thanthe known control line other, for example via terminal C30, is requiredadditionally.

FIG. 6 shows the special service common circuit 2 and is exactly thesame as FIG. 3 of the first embodiment except with respect to the minoraddition and alteration as the relay RS and terminal HDA and theterminals A22, B22 and C22 are connected directly to the service lineappearance L S. Therefore, its operations are substantially the same asthe operations of the first embodiment explained with reference to FIGS.2 and 3 and therefore only the differences between the circuitryillustrated in the aforementoined figures shall be explained. Further,the following description is with reference to FIG. 4.

CALL-WAITING SERVICE As explained with respect to FIG. 4, when thesubscriber SUB C is connected to the service subscriber SUB A who isspeaking With the subscriber SUB B, for the first time, the marker 6connects with the number group 7 and keeps the subscriber SUB Cconnected to the special service common circuit 2 through the trunk 9,switch frame 5 and service line appearance LS. In this case, in thespecial service common circuit 2 in FIG. 6, as the ground is connectedto the terminal C22 from the switchboard, by that ground connection, therelay RS operates through the ground terminal C22-rectifier D1-contact brelay RS-battery. When the relay RS operates, its contact rs is closed,the link controller 4 is grounded through the terminal BY through theearth-contact rl -contact b -contact by 2 -contact rscontactaafiterminal BY and only the above mentioned special service commoncircuit 2 is, kept vacant for the link controller 4. Then, as explainedwith reference to FIG. 4, when the marker 6 connects with the numbergroup 7 for the second time and receives the subscriber positioninformation of the service subscriber SUB A, a control line other thanthe known control line of the special service subscriber circuit 1corresponding to the service subscriber SUB A, that is, via terminal C30in FIG. 5 is connected to ground through the switch frame 5. When theground is connected, the link controller 4 is actuated through theground terminal C30contact e contact sp -contact ST. The link controller4 connects the special service common circuit 2 which has been alreadyobtained, and is indicated to be vacant, with the special servicesubscriber circuit 1 corresponding to the service subscriber SUB A byclosing the link 3 to form a speech connection between the servicesubscriber SUB A and the subscriber SUB C. The subsequent operations arethe same as in the first embodiment.

HOLDING SERVICE As explained in FIG. 4, while the service subscriber SUBA is speaking with the subscriber SUB B, the service subscriber SUB Aflashes the telephone receiver to call the subscriber SUB C. When thespecial service subscriber circuit 1 receives holding informationthereby, it actuates the link controller 4. When the link controller 4receives the holding information, it connects ground to the terminal HDAof each special service common circuit 2 shown in FIG. 6 and the relayRS of each special service common circuit 2 is operated through theground -terminal HDA-relay RS-battery. By the operation of the relay RS,the ground appears at the terminal BY of the special service commoncircuit 2 which is not being used through the ground -contact rl-contact b contact by 2 contact rs-contact un -terminal BY. The linkcontroller 4 obtains access to one of the vacant special service commoncircuits and connects it with the special service subscriber circuit 1corresponding to the service subscriber SUB A.

In the first embodiment, the service line appearance LS is connected tothe terminals A22, B22 and C22 of the special service common circuit 2through the special service subscriber circuit 1. But, in thisembodiment, the line appearance LS is connected directly to theterminals A22, B22 and C22 of the special service common circuit 2 inFIG. 6. Therefore, when the special service common circuit 2 isconnected to the special service subscriber cirwit 1, a loop through theterminal A22-cont-act em2 contact hd +coutact aa contact aa contact chmretardation coil RETl (ID-resistance R8-relay E2 (I)contact hdretardation coil RETl (I)-contact chm --contact rl contact c contact ice-terminal B22 is made for the service line appearance LS. Thereby theservice subscriber SUB A is connected to the switchboard through theservice line appearance LS and is connected to an originating callregister (not illustrated) by a known method so that a dial tone may beheard. The subsequent operations are exactly the same as in the firstembodiment.

What is claimed is:

1. A telephone switching system for providing normal coninection andspecial connection functions between telephone subscribers, comprising:

a plurality of special service subscriber circuits, each of saidsubscriber circuits associated with a respective special servicetelephone subscriber for receiving special service information requeststherefrom,

a special service circuit common to said plurality of special servicesubscriber circuits for transferring a normal connection between atleast one of said special service telephone subscnibers and a telephonesubscriber to a separate connection between said at least one of saidspecial service telephone subscribers and a third subscriber, commoncontrolled automatic switching means, each of said plurality of specialservice subscriber circuits being connected between said commoncontrolled automatic switching means and said special service telephonesubscribers by a first line appearance for said normal connection andsaid separate connection is established by a connection through saidspecial service common circuit, means interconnecting each of saidspecial service subscriber circuits with said special service circuit,and

said common controlled automatic switching means including means forinterconnecting either of said first line appearance or said specialservice line appearance with said telephone subscriber or said thirdsubscriber in accordance with control signals generated by said specialservice subscribers.

2. A telephone switching system as in claim 1 wherein each of saidspecial service subscriber circuits and said common controlled automaticswitching means are interconnected by said first line appearance andsaid special service line appearance.

3. A telephone switching system as in claim 1 wherein each of saidspecial service subscriber circuits is connected to said commoncontrolled automatic switching means by a first line appearance and saidspecial service circuit is connected to said common controlled automaticswitching means by said special service line appearance.

References Cited UNITED STATES PATENTS 2,819,345 1/1958 Nilsson 17918 BG3,242,266 3/ 1966 Strobelt et a1. 179-18BiD 3,355,555 11/ 1967Thelemaque l7-9-1 8 BG 3,488,751 1/1970 Gelke et al. 17918 BD 3,546,39312/1970 Joel 179-1-8 B WILLIAM G. COOPER, Primary Examiner

